$-\dfrac{6}{10} - \dfrac{2}{6} = {?}$
Answer: $ = - {\dfrac{6 \times 3}{10 \times 3}} - {\dfrac{2 \times 5}{6 \times 5}} $ $ = - {\dfrac{18}{30}} - {\dfrac{10}{30}} $ $ = - \dfrac{{18} - {10}}{30} $ $ = -\dfrac{28}{30}$